1. Field of the Invention
The present invention relates to a battery pack having a plurality of unit cells electrically interconnected, a method of manufacturing the battery pack and a method of controlling the battery pack.
2. Description of the Related Art
A battery pack having a structure in which a plurality of thin battery cells (unit cells) are stacked together and interconnected has been known as disclosed in Japanese Patent Application Laid-Open No. 2003-346748 (Patent Document 1).
The battery pack described in the Patent Document 1 is structured such that a plurality of thin battery cells stacked together is contained in a box. The thin battery cells in the box are controlled so as to have uniform values of voltage.
When a specific thin battery cell among the plurality deteriorates to a greater degree than the other thin battery cells, the deteriorated thin battery cell must be replaced with a new one. To replace such a specific deteriorated thin battery cell, substantial effort is required to take the battery pack from the box and to disassemble it. Also, it is not economical to replace the whole battery pack when only one of the plurality of thin battery cells has deteriorated. For this reason, it is desirable to use thin battery cells that deteriorate at similar rates.